Today's energy generating system, for example, a photovoltaic system, mainly includes a photovoltaic array, an electric power regulator, a distribution box, a storage battery, etc., in which the electric power regulator, for example, includes a grid-tied protection device, an inverter or a system controller. Divided according to the types of the system, the photovoltaic systems can be divided into a grid-tied type, an independent type, and a mixed type photovoltaic system. Generally, the photovoltaic array is a solar cell module array formed by connecting solar panels in series and parallel, which is used for converting the solar energy into electric energy. However, in case that the solar panels are in a sunshine-shielding state or output voltages and currents of the solar panels are not matched, an output power of the photovoltaic array is decreased. Therefore, a control circuit used for tracking a maximum power point (MPP) is generally added to the system to obtain a maximum power output by the photovoltaic array.